The fire, which started on Nov. 8, killed 85 people and destroyed nearly 19,000 homes, businesses and other buildings. The California Department of Forestry and Fire Protection, or Cal Fire, said on Wednesday that, after a “very meticulous and thorough investigation,” it had determined that the Camp Fire was caused by “electrical transmission lines owned and operated” by PG&E. The company had said in February that its equipment had probably caused the fire.

PG&E, the state’s largest electricity utility, filed for bankruptcy protection in January, saying that it faced an estimated $30 billion in wildfire liabilities. In a recent filing to securities regulators, the company estimated it would have $10.5 billion in liabilities for damage caused by the Camp Fire.

State officials said the fire had started near Pulga in Butte County, about 95 miles north of Sacramento, and spread rapidly, destroying the town of Paradise. Cal Fire said it had forwarded its report to the Butte County district attorney’s office.

PG&E said in an earlier filing that the Butte County district attorney and California’s attorney general had opened a criminal investigation into the Camp Fire.

In a statement on Wednesday, PG&E said that it had not yet reviewed Cal Fire’s report but that it “is consistent with the company’s previous statements.”

“Our hearts go out to those who have lost so much, and we remain focused on supporting them through the recovery and rebuilding process,” the statement said. “We also want to thank the brave first responders who worked tirelessly to save lives, contain the Camp Fire and protect citizens and communities.”

[Read more about a 99-year-old PG&E tower that the company let stand even after it had acknowledged that such structures were at risk of collapse.]

PG&E previously said that it recognized “that more must be done to adapt to and address the increasing threat of wildfires and extreme weather” and that it was stepping up inspections, tree trimming and maintenance. The company recently appointed a new chief executive and added 11 new directors to its board.

The Camp Fire underscored the increasing threat that wildfires pose to California as climate change has intensified droughts and heat waves. In April, Gov. Gavin Newsom outlined a plan to reduce the risk of wildfires and find new ways to shoulder the enormous costs of the fires.

Lawyers for victims of the fire said the state’s report on Wednesday confirmed what many people had long suspected.

“Now the day of reckoning has come,” said Frank Pitre, a lawyer for victims who is based in the Bay Area. “If PG&E wants to do the honorable thing, they should stop spending tens of millions of dollars in bankruptcy court and begin putting together the plan to compensate the victims.”

In bankruptcy, the claims of wildfire victims will compete with the claims of bondholders and other PG&E creditors. People who lost their homes to the Camp Fire will probably not know how much the company will pay them for many months and possibly even years.

Some survivors like Randi Hall, who lost her home in Paradise and now lives in a recreational vehicle with her boyfriend, her young daughter and a puppy, have said PG&E appears to be shirking its obligations to victims in bankruptcy court.

“If I caused the fire, I wouldn’t be able to file bankruptcy and I wouldn’t be able to make other people pay for it,” Ms. Hall said in an interview last week. “Why does a company that has so many millions of dollars in insurance get to do it?”

Separately on Wednesday, Mr. Newsom criticized PG&E for how it has handled its bankruptcy case, saying in a court filing that the utility “has not demonstrated that it understands the gravity and urgency of the situation.”

At a hearing scheduled for next Wednesday, the court will consider a request by PG&E for six more months to file its reorganization plan. The company has “not earned the privilege” of such a long delay, the governor’s office argued, because it has failed to rectify “two decades of mismanagement, misconduct and failed efforts to improve a woeful safety culture.”

Instead, Mr. Newsom suggested that the court extend the deadline to mid-August.

Many state lawmakers have called for tougher oversight of the company, which was convicted of six felonies after a 2010 gas pipeline explosion near San Francisco. Its equipment has been blamed for starting several large wildfires in recent years.

“It will be a heavy price to pay if they do not change their way of doing business,” said State Senator Jerry Hill, a Democrat who represents San Francisco. “We have to guarantee the safety of our citizens.”

Lauren Hepler and Jill Cowan contributed reporting.

A version of this article appears in print on , on Page B6 of the New York edition with the headline: Power Lines Blamed in Record Calif. Fire. Order Reprints | Today’s Paper | Subscribe